Spellchecking some comments

This PR attempts to clean up some minor spelling mistakes in comments

compiler/rustc_expand/src/config.rs

@@ -414,7 +414,7 @@ impl<'a> StripUnconfigured<'a> {
             };
             trees.push((AttrAnnotatedTokenTree::Token(bang_token), Spacing::Alone));
         }
-        // We don't really have a good span to use for the syntheized `[]`
+        // We don't really have a good span to use for the synthesized `[]`
         // in `#[attr]`, so just use the span of the `#` token.
         let bracket_group = AttrAnnotatedTokenTree::Delimited(
             DelimSpan::from_single(pound_span),

compiler/rustc_expand/src/expand.rs

@@ -1847,7 +1847,7 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
         if node.is_expr() {
             // The only way that we can end up with a `MacCall` expression statement,
             // (as opposed to a `StmtKind::MacCall`) is if we have a macro as the
-            // traiing expression in a block (e.g. `fn foo() { my_macro!() }`).
+            // trailing expression in a block (e.g. `fn foo() { my_macro!() }`).
             // Record this information, so that we can report a more specific
             // `SEMICOLON_IN_EXPRESSIONS_FROM_MACROS` lint if needed.
             // See #78991 for an investigation of treating macros in this position

compiler/rustc_expand/src/lib.rs

@@ -36,7 +36,7 @@ crate mod mbe;
 // HACK(Centril, #64197): These shouldn't really be here.
 // Rather, they should be with their respective modules which are defined in other crates.
 // However, since for now constructing a `ParseSess` sorta requires `config` from this crate,
-// these tests will need to live here in the iterim.
+// these tests will need to live here in the interim.
 
 #[cfg(test)]
 mod tests;

compiler/rustc_expand/src/mbe.rs

@@ -41,7 +41,7 @@ impl Delimited {
     }
 
     /// Returns a `self::TokenTree` with a `Span` corresponding to the closing delimiter. Panics if
-    /// the delimeter is `NoDelim`.
+    /// the delimiter is `NoDelim`.
     fn close_tt(&self) -> &TokenTree {
         let tt = self.all_tts.last().unwrap();
         debug_assert!(matches!(